With development of TFT-LCD (Thin Film Transistor Liquid Crystal Display) technology and progress of industrial technology, as well as reduction of production cost and increasing perfection of manufacturing process of liquid crystal display devices, liquid crystal display technology has taken the place of cathode ray tube display technology as mainstream technology in daily display field. Liquid crystal display devices have become ideal display devices in the market and in the minds of consumers due to their inherent advantages.
A liquid crystal display device is a nonluminous passive display device in itself, and depends on a backlight module to achieve the display function. A structure of a display device in the prior art is now described with reference to FIGS. 1 and 2, FIG. 1 is a sectional view showing the structure of the display device in the prior art; and FIG. 2 is a schematic diagram of a lateral structure of the display device shown in FIG. 1. From FIGS. 1 and 2 it can be seen the display device comprises a housing 11, a display panel 12, and a backlight module 13 located at a side of the display panel 12, wherein the backlight module 13 is a quite important component in an LCD module, because on the one hand, performance of the backlight module 13 will have direct effect on LCD imaging quality, and on the other hand, cost of the backlight module 13 accounts for 3-5% of that of the LCD module, and power consumption thereof accounts for 75% of that of the LCD module. A highly-sophisticated large-size LCD requires high-performance backlight technology matched therewith, and therefore while LCD industry is trying to expand new application fields, high performances (such as high luminance, low cost, low power consumption, lightness and thinness, etc.) of backlight technology also play an important backstage role.
The backlight module 13 has the characteristics of high luminance, long service life, uniform light, etc. At present, backlight modules mainly include the following three types according to different luminous principles: electroluminescence (EL), cold cathode fluorescent lamp (CCFL) and light-emitting diode (LED) types; in addition, backlight modules can also be divided into edge type and direct type ones according to different distribution locations of light sources. Among them, LED backlight modules have become a mainstream in current development of backlight modules due to their advantages of energy conservation, environment-friendliness, long service life, small volume, wide color gamut, etc.
Nevertheless, backlight modules are not without shortcomings. LEDs are photoelectric devices, and only 15%-25% of electric energy is converted to light energy during their operation, and the rest of electric energy is almost all converted to heat, and the generated heat causes temperature of display devices to rise, so the problem of heat dissipation of backlight modules cannot be ignored. In the prior art, heat dissipation of backlight modules is mainly implemented in two ways, namely passive cooling and active cooling. Active cooling mainly involves increasing air flow velocity at surfaces of radiation fins by fans or other similar devices, to quickly take away heat from the radiation fins, and to further improve heat dissipation efficiency. Passive cooling means dissipating heat generated by LEDs by means of natural convection between outer surfaces of lamps (made of aluminum with high thermal conductivity) themselves and air. For passive cooling, radiation fins made of copper-aluminum alloy with relatively good heat conductivity and low cost are mainly adopted for heat dissipation, to achieve the function of protecting circuit components. For a passive cooling way, design and assembly thereof are simple, and integration into mechanical structure design of lamps is easy; protection level requirement of circuit components is relatively easy to achieve; and with low cost, it is currently a widely used heat dissipation way.
However, whichever of active cooling and passive cooling is adopted, heat generated by a backlight module cannot be used sufficiently, and energy is wasted.